U.S. Homeland Security chief Janet Napolitano resigning

Former Arizona governor and attorney general was appointed by Obama in 2008

U.S. Homeland Security Secretary Janet Napolitano testifies on Capitol Hill in Washington on April 18, 2013, before the House Homeland Security Committee. Napolitano is reportedly resigning from her post. (Evan Vucci/Associated Press)

U.S. Homeland Security Secretary Janet Napolitano, who led the burgeoning department through a host of policy changes in the post 9/11 era, is resigning.

Napolitano, just the third person to lead the 10-year-old Homeland Security department, told her senior staff Friday she would be leaving. She will become the president of the University of California system, which includes UCLA and the University of California, Berkeley, among other campuses. The University of California also announced Napolitano's nomination to be the 20th president of the statewide system.

"The opportunity to work with the dedicated men and women of the Department of Homeland Security, who serve on the front lines of our nation's efforts to protect our communities and families from harm, has been the highlight of my professional career," she said in a statement. "After four plus years of focusing on these challenges, I will be nominated as the next president of the University of California to play a role in educating our nation's next generation of leaders."

"I thank President Obama for the chance to serve our nation during this important chapter in our history," Napolitano said, "and I know the Department of Homeland Security will continue to perform its important duties with the honour and focus that the American public expects."

Napolitano, a former Arizona governor and attorney general, was appointed by U.S. President Barack Obama in 2008. She had led the department through a series of policy changes with respect to protecting the public safety, including a focus on enforcing immigration laws.

Under her tenure, DHS implemented a widespread policy of using prosecutorial discretion when dealing with immigrants arrested for being in the country without permission. She said her department needed to focus its scarce resources on criminals and those who posed a threat to public safety and national security.

She also helped establish a plan to provide temporary relief from deportation for thousands of young immigrants who arrived in the United State illegally and who don't have legal status.